1. Field of the Invention
This invention relates to an electronic apparatus having a power supply unit for supplying electric power to a driving unit performing a predetermined operation of the apparatus, and, since there is the possibility that the output of the power supply unit for the driving unit fluctuates, having control means for performing driving control of the driving unit.
2. Description of the Related Art
Heretofore, in various kinds of electronic apparatuses, batteries or power supply circuits which convert alternating current from a commercial AC power source into direct current have been used as power supplies of the apparatuses. It is common to feed semiconductor devices and driving systems, such as motors, solenoids and the like, of electronic apparatuses via a predetermined stabilization, such as constant-voltage control, constant-current control and the like. There are problems, however, in that some of the circuits, such as constant-voltage power supplies, constant-current power supplies and the like, are inferior in power efficiency, and the configuration of an apparatus becomes complicated. Hence, it is preferable to dispense with these circuits.
On the other hand, in various kinds of electronic apparatuses, there is now widely being used a configuration in which each unit of an apparatus is controlled by a programmable control unit using a microprocessor and the like. In this kind of apparatus, a control table storing data for determining driving conditions of a driving system is provided within a program memory, data, such as ambient temperature, humidity, various kinds of switch settings and the like, are input to the table, and driving voltage, driving current, driving period and the like of motors, solenoids and the like in the driving system are determined.
In such a configuration, it is possible to perform control such that normal operations can be performed even if there are fluctuations in voltage, according to the configuration of the control table. If a stabilizing power supply is not used, data construction of the control table must be provided so as to be operable within the entire range of fluctuating voltage or current in the power source.
When such a table configuration is provided, it is necessary to set operation conditions making allowance for fluctations in the power source. Hence, there are problems in that it is necessary to increase the driving time of the driving system, or to increase the driving voltage, driving current and the like, and the most suitable control can not be performed relative to power efficiency and operation speed.